5,395 research outputs found
Environmentally-induced discharge transient coupling to spacecraft
The Hughes SCREENS (Space Craft Response to Environments of Space) technique was applied to generic spin and 3-axis stabilized spacecraft models. It involved the NASCAP modeling for surface charging and lumped element modeling for transients coupling into a spacecraft. A differential voltage between antenna and spun shelf of approx. 400 V and current of 12 A resulted from discharge at antenna for the spinner and approx. 3 kv and 0.3 A from a discharge at solar panels for the 3-axis stabilized Spacecraft. A typical interface circuit response was analyzed to show that the transients would couple into the Spacecraft System through ground points, which are most vulnerable. A compilation and review was performed on 15 years of available data from electron and ion current collection phenomena. Empirical models were developed to match data and compared with flight data of Pix-1 and Pix-2 mission. It was found that large space power systems would float negative and discharge if operated at or above 300 V. Several recommendations are given to improve the models and to apply them to large space systems
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Concurrent Chemoradiation for Vaginal Cancer
Background: It is not known whether the addition of chemotherapy to radiation therapy improves outcomes in primary vaginal cancer. Here, we review clinical outcomes in patients with primary vaginal cancer treated with radiation therapy (RT) or concurrent chemoradiation therapy (CRT). Methods: Seventy-one patients with primary vaginal cancer treated with definitive RT with or without concurrent chemotherapy at a single institution were identified and their records reviewed. A total of 51 patients were treated with RT alone; 20 patients were treated with CRT. Recurrences were analyzed. Overall survival (OS) and disease-free survival (DFS) rates were estimated using the Kaplan-Meier method. Cox regression analysis was performed. Results: The median age at diagnosis was 61 years (range, 18–92 years) and the median follow-up time among survivors was 3.0 years. Kaplan-Meier estimates for OS and DFS differed significantly between the RT and CRT groups (3-yr OS = 56% vs. 79%, log-rank p = 0.037; 3-yr DFS = 43% vs. 73%, log-rank p = 0.011). Twenty-three patients (45%) in the RT group had a relapse at any site compared to 3 (15%) in the CRT group (p = 0.027). With regard to the sites of first relapse, 10 patients (14%) had local only, 4 (6%) had local and regional, 9 (13%) had regional only, 1 (1%) had regional and distant, and 2 (3%) had distant only relapse. On univariate analysis, the use of concurrent chemotherapy, FIGO stage, tumor size, and date of diagnosis were significant predictors of DFS. On multivariate analysis, the use of concurrent chemotherapy remained a significant predictor of DFS (hazard ratio 0.31 (95% CI, 0.10–0.97; p = 0.04)). Conclusions: Vaginal cancer results in poor outcomes. Adequate radiation dose is essential to ensure curative management. Concurrent chemotherapy should be considered for vaginal cancer patients
Marine Managed Areas Workshop report, Penang, Malaysia, 18-19 January, 2011
Establishment of a working group of regional experts in Marine Protected Areas (MPAs); inventory and status of existing MPAs; gap analysis;establishment of common data requirements and protocols;development of a regional action plan;training and capacity building; outreach activities; proposal f0r management of existing and creation of new MPAs
Ultra Wideband Channel Characterization and Ranging in Data Centers
This paper presents a detailed measurement based characterization of the Ultra Wideband (UWB) channels in a data center environment and examines the accuracy of direct ranging using Time of Arrival (ToA) measurements. Modern data centers present a unique indoor environment that to our knowledge has not yet been characterized. Our ranging experiments indicate that it is possible to achieve an accuracy of fraction of a meter via direct ranging and point to the feasibility of locating individual servers using more sophisticated cooperative ranging
Involvement of extension personnel in implementing social forestry programmes
In a country like India, where the population is high and resources are limited, social forestry is an instrument for
rural development, particularly for the poor people. Thus social forestry is identified as a forestry of the people, by
the people and for the people
Report of the Marine Protected Areas Working Group meeting, Penang, Malaysia, 11-12 February, 2014
The objectives of the workshop were to review and update Marine Protected Area (MPA) data, finalise policy briefs for each country and recommend future actions and policies for sustainable management of MPAs
Spin-Hall effect and circular birefringence of a uniaxial crystal plate
The linear birefringence of uniaxial crystal plates is known since the 17th
century, and it is widely used in numerous optical setups and devices. Here we
demonstrate, both theoretically and experimentally, a fine lateral circular
birefringence of such crystal plates. This effect is a novel example of the
spin-Hall effect of light, i.e., a transverse spin-dependent shift of the
paraxial light beam transmitted through the plate. The well-known linear
birefringence and the new circular birefringence form an interesting analogy
with the Goos-H\"anchen and Imbert-Fedorov beam shifts that appear in the light
reflection at a dielectric interface. We report the experimental observation of
the effect in a remarkably simple system of a tilted half-wave plate and
polarizers using polarimetric and quantum-weak-measurement techniques for the
beam-shift measurements. In view of great recent interest in spin-orbit
interaction phenomena, our results could find applications in modern
polarization optics and nano-photonics.Comment: 16 pages, 8 figures, to appear in Optic
Hypohidrotic Ectodermal Dysplasia with total anodontia: a case report
Ectodermal dysplasia is a hereditary disorder that occurs as a consequence of disturbances in
the ectoderm of the developing embryo. The triad of nail dystrophy, alopecia or hypotrichosis and palmoplantar
hyperkeratosis is usually accompanied by a lack of sweat glands and a partial or complete absence of primary and/
or permanent dentition. A case report illustrating the prosthetic rehabilitation of a seven year old boy with hypohidrotic ectodermal dysplasia associated with total anodontia is presented
Long-Range Navigation on Complex Networks using L\'evy Random Walks
We introduce a strategy of navigation in undirected networks, including
regular, random, and complex networks, that is inspired by L\'evy random walks,
generalizing previous navigation rules. We obtained exact expressions for the
stationary probability distribution, the occupation probability, the mean first
passage time, and the average time to reach a node on the network. We found
that the long-range navigation using the L\'evy random walk strategy, compared
with the normal random walk strategy, is more efficient at reducing the time to
cover the network. The dynamical effect of using the L\'evy walk strategy is to
transform a large-world network into a small world. Our exact results provide a
general framework that connects two important fields: L\'evy navigation
strategies and dynamics on complex networks.Comment: 6 pages, 3 figure
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Direct evidence for thymic function in adult humans.
The understanding of human thymic function and evaluation of its contribution to T cell homeostasis are matters of great importance. Here we report the development of a novel assay to quantitate the frequency and diversity of recent thymic emigrants (RTEs) in the peripheral blood of humans. Such cells were defined by the presence of T cell receptor (TCR) rearrangement deletion circles (DCs), episomal byproducts of TCR-beta V(D)J rearrangement. DCs were detected in T cells in the thymus, cord blood, and adult peripheral blood. In the peripheral blood of adults aged 22 to 76 years, their frequency was highest in the CD4(+)CD45RA(+) CD62L(+) subpopulation of naive T cells. TCR DCs were also observed in other subpopulations of peripheral blood T cells, including those with the CD4(+)CD45RO(-)CD62L(+) and CD4(+)CD45RO(+)CD62L(+) phenotypes. RTEs were observed to have more than one Vbeta rearrangement, suggesting that replenishment of the repertoire in the adult is at least oligoclonal. These results demonstrate that the normal adult thymus continues to contribute, even in older individuals, a diverse set of new T cells to the peripheral circulation
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